Haynes says 190'F. Bentley is silent. Volvo FAQs says 198'F. However, Amazon keeps giving me error messages of incompatibility when I select that temperature.

Also, FAQs don't recommend a brand. I like Stant.

I will be running the engine stock.

Can anyone recommend a thermostat brand, model, and temperature range?

BUY FROM FCP GROTON,,THEYVE THE RIGHT STUFF,,,GUARANTEED FOR LIFE

As for a lifetime warranty - does it cover engine damage?

Some lifetime warranties come about because no one would but the product without that incentive.

I favor Volvo parts, and like Eric's advice.

I read somewhere - when I needed a thermostat for our '90 744 TI - in a reliable source that the higher temperature is for normally aspirated engines and the lower temperature is for turbo engines.

This makes sense because there is more heat in the engine compartment of turbo engines and the intercooler blocks and uses some of the cooling air.

Also, in older engines, once the thermostat opens, it never closes again, in newer more efficient engines, the thermostat may close again on the highway on colder days - hence, the different temperatures - to keep NA engines at a proper operating temperature.

Years ago, BMW used a bypass thermostat on some of their engines, that bypassed the radiator on very cold conditions, like very cold up in the mountains.

Twice, in out 850s, the temperature began to go below normal in the winter - in each case - two different cars - their thermostats failed open.

I am under the impression that the thermostats that Volvo used were designed to fail open.

I strongly recommend that you make sure to buy a thermostat that fails open.

Thanks.

How do I know if a thermostat fails open?

Thanks

IT will break & jam open or closed

You will know if it fails open as the car won't properly heat up. I had one stick open with the outside temperature just above freezing. It was a long cold drive to the parts store and back with no heat.

Hi,

That is a good question and the best answer is, you won’t truly know.

The idea of using physics in the design, is to work with something, that will reliably happen every time and not fail at all. Like gravity!

The working part of the thermostat is the chamber in the center that expands when heated.
This chamber has to be able to expand and contract due to a compound inside.
It is basically that simple for something short of a true fluid in the operating temperature range desired.
The only term I know of is, it is called a WAX. This concoction is easier to contain if it stays very viscous. In this state it does not squeak by the seals like an oil would.
That little engine inside the thermostat has to be made tight and the parts must expand together. That’s why I like seeing the copper chamber and the brass together. Brass contains copper and both respond well to heat.
They are dissimilar enough not to gall when moving.

When I helped make the three “low light” lenes, to fit a Mitchell high speed camera of the 1930’s. This required special bodies be made to hold Nikon glass lenes. In 1982, it cost him $80,000 for them. After Star Wars, they are probably priceless, in retrospect.
This was for the George Lucas company, at the time it was Industrial Light and Magic.

We used aluminum but three different grades or mixtures of aluminum alloys throughout. The alignment of the lenses depended on a “lapped in engagement” of one thread started 16 times. The total travel was way longer than one inch in less than one revolution or turn between the two barrels for focusing.
So I LEARNED and know a thing or two about metal fitment from experience of machining and repairing.

You can think of it to be similar but opposite to an oil used in the fan clutch, that I have read, is of a silicone base fluid that responds more rapidly in viscosity to slight temperature changes. I figure it’s because it operates at lower temperatures ranges it is the fluid of choice for its physical properties.

As far as a fool proof failure design, to fail in the open position, the design would have to incorporate a “cam over” design to reach a certain point past its normal operating range and basically break itself open.
On the one Wahler I had break after 17 years did that. It broke the bridge that held the whole apparatus together. Just like a Jack-in-theBox toy except there was no resetting it.
It didn’t overheat or anything it just plainly fatigued.

As far as the temperatures of these thermostats you choose to use there is some hair splitting going on.
We are talking a ten degree Fahrenheit spread from the low to a high of 87C = 188F, 89C and 92C = 197F
Almost any car is 195 F to 210 F nowadays.
With a proper working cooling system none of the upper ones should cause an issue. Overheating starts around 240 + F. You will be in the Red Zone for sure!
I read where PlanetMan likes 87C but his customers are in the Southwest.
Wagonmeister likes 87 or 89C Calorstat thermostats and he is in the same region.
My error on names, CALORSTAT by Vernet =potentiometers versus Calories and caloric count seems to get twisted in my brain all the time.

Apparently their cars pass smog and with some creedence of their trade given to them, I say, there are lots of bugs and hard water down there that ends up in these old cars radiators!
Maybe they like the cooler margin of error to be on the customers side.

Besides cold mornings are not plentiful there but a warmup is not always included in most commutes.
I live at a slower pace, thank you!

Phil

Hi,

I like WAHLER in a 92 degree centigrade value. They come boxed and are made of brass and copper of which both are made of so the materials work the same as one. They are a wee bit more expensive and were OEM from Volvo in 249's. They have been bought by Borg Warner and still made in Germany.
All three makes seem to come listed for our cars through parts houses in more popular 87 or 89 centigrade. I think this is because their warehouses want to keep less of an inventory of different brands so it forces you to select an inferior product that makes them more profit with less shelf time investment.
I have to hunt for the 92 degree and the right price. I usually find them around $15. Some will scam you into twice that if they have to order it. I don't bite as I now see what's happening and get three for stocking up for my fleet of six.

The last one I bought still came with a manufacturing date stamped on them. I like that!
Many of my thermostats get replaced when I think it's about time. That's around 15 years. I had one fail in the open position after 17 years so I backed up a couple years and use it as my scary line now!
The crown brace breaks its spot weld. If a thermostat fails I love it to be in the open positions.

Caloric and Stant are made of different Unknown metal materials and can have more of a sticking issue. IMHO.

Stants have always failed shut, in my '74 Ford pickup causing overheating. I have gone through three of those at about five years each along with two replacement upper tanks on the radiators.
If I ever put it back on the road I'm not using a Stant.
I hope someone else makes one now!

Both Stant and Caloric brands are sold in department store parts house hanging on a peg for people to handle or drop on the floor.
In many cases I have seen this happen with unattended adults and kids!
In those many cases, including myself having one sliding off a plastic jug, I have witness those being dropped or knocked off the peg and laying in stuff or put back on a peg at any other place.
I believe if one realizes that these should be considered precision stampings and carefully adjusted wax expanding instruments they would pick another one without dents on the package to purchased.

I have had three Calorics fail, one closed shut and the exhaust pipe was red hot. The other two got lazy and would not not fully close down during shut downs. So, therefore running the engine colder and the gauge needle lower and closer to 7:30 or maybe 8:00.
The LH's will run the motor richer than necessary and seldom if ever shoot a code close for it. You will hardly know with in town mileage but on the open road it's a mile or two more per gallon difference depending on 87/ 89 to the 92 and the oil smells fresher with less gasoline/oil fragrance.

When Volvo put in the temperature faker they made it read straight across at nine o clock for a normal temperature. From there it only moved in stages or steps of which many do not like a sudden jump so we remove the board.

In the early red block year of my 1978 that has Lambda emissions it came with a 92 degree and ran horizontal on the gauge. It has always read there within a needle width for all its years.
On my other newer cars I had to experiment with different temperatures due to not being able to get WAHLERS all the time or being sold a bill of goods due to the explanation above.
I have since read that the people into building today's emissions vehicles that they want the combustion chamber to run no less than around 200 degrees Fahrenheit as quickly as possible. 92 degrees centigrade puts you right there. 197 degrees or Horizontal on the normal temperature gauge!

So there you have my nickels worth and since they don't make money out of brass or even copper anymore, that's the jest of that!
Ps: the last ones I got were from FCP GROTON, I think, on sale. 6 months or better ago.

Phil

Thanks.

I found a Mahle with a lifetime warranty at Autozone for $15 or so. Thoughts about that?

Hi,

I have never seen a Mahle but it is a manufacturing parts vendor that Volvo has used for engine components. They are at least an aftermarket company to the best of my knowledge.
Probably a worthy consideration at that price though.

Be glad you don't own some other make of new car as the sky is getting to be the normal limit for them! Plain nuts for their special configurations!

I have not reach a point with my cars to investigate pistons, rings or bearings for the crank and rods.
Mahle might have someone else make them like Beck Arnely does for them to rebrand as well?
Beck Arnely buys end of runs, overstocks and so forth with contracts.
I suspect AZ does likewise and both have a box and labeling company do the rest.

The lifetime warranty does not make for a higher quality part as its only an insurance policy sold to you in the price of the part. Harbor Freight will politely sell you an extended warranty on pricey equipment. Many of their hand tools carry a lifetime warranty. Who's life is anyone's guess.
Just use your buyer beware instincts in these cases. Just having you ask is a good sign you have that quality.

Insurance is a business of statistics as are the odds in gambling that the part will not comeback with the original purchaser. Keep any and all receipts and hope they don't fade or the AZ computers suffer a castrophic deletion like Facebook.
Today's cars go out of graces with this generation of buyers and instantaneous response for what they want it to do. As soon as they start having moments of an unexplained hiccup, trade payments!

You got love these 240's as they were designed and built to do just what they're doing! There are tons of various scrapped car models that haven't done that in years!

From what I can tell in the junkyards the new Volvos have slipped a tad and maybe that's why their going big towards electric models. I hear crying about maintaining and some repair jobs.

Time will tell us!

Phil

If the pictures are accurate at the Autozone website, the Mahle is a made in Germany by Wahler and opens at 87°C.

FYI, the recommended opening temperature is 87°C.

I only sell/install OE Volvo, Wahler, Varnet and Calorstat thermostats all of them made in the EU for my customers Volvos.

Experience has shown that these work while other brands don't.

--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com